I think you're confusing DDIO with DCA. DDIO is Intel's mechanism of allocating L3 cache ways to DMA, and works for any vendor's card. DCA is an older set of

I think you're confusing DDIO with DCA. DDIO is Intel's mechanism of allocating L3 cache ways to DMA, and works for any vendor's card. DCA is an older set of steering hints that cause per-TLP steering hint flags to influence whether or not a DMA write ends up in the CPU cache. DCA is highly targeted, and much more effective in realistic workloads because you can be smart, and cache just descriptors and packet header DMA writes (eg, metadata). With DDIO, you end up caching everything, and with a limited number of cache ways, you end up often caching nothing, because later DMAs push earlier ones out of cache before the host can use the data. At a previous employer, we figured out the DCA steering hits and implemented it in our NIC. Thankfully enough of our PCIe implementation was programmable to allow us to do this.